This invention relates to a lifting mechanism for removing the cover from the top of a heated spa and, in particular, to a light-weight lifting mechanism capable of removing a heavy spa cover with a minimum amount of distortion of the lifting members.
The use of outdoor spas or hot tubs has become widespread, particularly in warm climate regions. Most outdoor spas are equipped with covers which serve to prevent debris and the like from contaminating the tub water when the spa is not in use. In addition, the covers are also designed to retain heat and thus maintain the bath water temperature at a desired level. As a consequence, spa covers tend to be relatively heavy devices that are difficult to install and remove from the tub.
Lifting devices have been developed to aid in the covering and uncovering of spas and hot tubs which can be operated with varying amounts of difficulty by a single individual. One such lifting device is disclosed in U.S. Pat. No. 5,048,153 to Wall et al. and another is disclosed in U.S. Pat. No. 5,131,102 to Salley et al. In both of these prior art devices, a pair of pivotally mounted opposed arms are arranged to engage the tub cover and simultaneously lift the cover and swing it clear of the tub, thereby uncovering the tub to provide unhindered use of the spa. The cover remains in engagement with the lifting mechanism when the tub is being utilized and the mechanism is again brought into play to restore the cover to a closed position when the tub is not being used.
Although these prior art devices provide a mechanical advantage that allows one person to remove and restore a heavy spa cover, the structural frame members of the device, nevertheless, tend to bend or become distorted when the lifting frame is placed in operation. Because most spas are relatively large or bulky, an individual is usually able to pull against only one side of the frame during the covering or uncovering operation. This places a high bending moment or torque upon the frame components causing the frame to twist. This results in one side of the cover being lifted before the other producing unwanted rubbing between the cover and the lifting frame components. As can be seen, this constant bending of the lifting frame components causes undue fatigue on the distorted member leading to early equipment failure and costly repairs.